Advance mechanism

Abstract

An advance mechanism for perforated materials such as film strips. The mechanism advances the material through a path of light and includes a support structure adapted to be aligned with a source of light so that the light passes through a rotating aperture in the support and scans line of print. The structure is provided for directing the perforated material along a pathway into and out of vertical alignment with the aperture. A pawl mechanism including a spring on a support adjacent to the aperture and is in a normally retracted position in alignment with a slot adjacent to the aperture in the support. Drive structure is provided for cooperating with a biasing spring and directing the pawl mechanism through the slot into engagement with a perforation in the material and then along the slot a predetermined distance to advance the material. Thereafter the pawl mechanism is released by the drive structure to permit the spring to return the pawl to the retracted position out of the slot. Further, structure is responsive to release of the pawl mechanism and retraction of the pawl through the slot to return the pawl to the normal retracted position. The movement of the biasing spring along the slot is restricted by stop means including at least one upstanding portion on the spring of an enlarged surface area for engagement with a corresponding surface area on the support. Furthermore, a flexible coupling is mounted on the shaft of the drive motor to uniformly index the rotation in the above mentioned member.

I claim: 
     
       1. An advance mechanism for perforated materials for advancing the material thourgh a path of light comprising: a support structure adapted to be in line with a source of light so that light passes through an aperture in the support;   material support and advance means for directing the perforated material along the pathway into and out of alignment with the aperture;   a pawl mechanism including spring means on the support adjacent the aperture and normally positioned in a normal retracted position in alignment with a slot adjacent to the aperture in the support;   drive means for cooperating with the material advance means and for biasing the spring and directing the pawl mechanism through the slot into engagement with a perforation in the material and then along the slot a predetermined distance to advance the material and then releasing the pawl mechanism permitting this spring to return the pawl to the retracted position out of the slot;   return means responsive to release of the pawl mechanism and retraction of the pawl through the slot to return the pawl to normal retracted position;   limit means positioned on the support and on the pawl mechanism to restrict the distance of movement of the pawl mechanism along the length of the slot;   the limit means including at least one enlarged receiving surface on the support and a corresponding enlarged bearing surface on the pawl mechanism whereby movement of the pawl mechanism along the slot a predetermined distance will bring the enlarged bearing surfaces into engagement and stop further movement of the advance mechanism with respect to the slot and with the engagement between the enlarged surfaces distributing the force applied in limiting the movement of the pawl mechanism;   the pawl mechanism including an elongated leaf spring mounted on the support and having a downwardly extending pawl intermediate its ends in alignment with and in position for extension through the slot in the support;   a drive projection extending from the side of the elongated leaf spring opposite to the pawl and in position for engagement by a portion of the drive means;   the elongated leaf spring being slidably positioned on the support so that engagement of the drive means with the drive projection and application of a force thereto will bias the leaf spring until the pawl extends through the slot into engagement with a perforation in the perforated material and then the leaf spring will be slidably moved by the drive means and the perforated material accordingly advanced, and when the drive means is disengaged from the leaf spring, the leaf spring will return to its initial configuration with the pawl disengaged from the perforated material and withdrawn through the slot in the support whereupon the return means can return the leaf spring to the normal retracted position; and   the drive projection being resilient and capable of acting as a spring independent of the remainder of the leaf spring to facilitate continued movement of the drive means after the movement of the advance mechanism has been stopped to permit disengagement therebetween and to cooperate in permitting the leaf spring to flex and disengage the pawl from the perforated material thereby preventing damage to the perforated material when the perforated material is manually pulled or when a perforation is not properly aligned with the pawl.   
     
     
       2. The invention in accordance with claim 1 wherein the limit means on the support includes a pair of spaced end walls on the support and with an aperture in each end wall aligned with the elongated leaf spring member to permit the passage therethrough as the leaf spring member is slid with respect to the slot, a lateral stop extending from the elongated member between the end walls with the stop being shorter than the distance between the end walls so that the elongated member is permitted to slide the distance equal to the difference in the length of the stop and the distance between the end walls, at least one end of the lateral stop terminating in an upstanding tab forming an enlarged bearing surface which is substantially parallel to the adjacent end wall so that when it engages therewith the force therebetween will be distributed over an enlarged area. 
     
     
       3. The invention in accordance with claim 2 wherein the drive projection on the elongated members is an upwardly extending prong which extends in the direction of movement of the elongated member when subjected to a force from the drive means. 
     
     
       4. The invention in accordance with claim 2 wherein the return means is a helical spring attached to one end of the elongated leaf spring member and at the other end to the support, the helical spring being relaxed when the leaf spring is in the normal position with the pawl in the normal retracted position whereupon sliding of the elongated member to advance the perforated material biases the helical spring so that when the leaf spring is released the helical spring will return to the normal relaxed position and slide the leaf spring back to the initial position. 
     
     
       5. The invention in accordance with claim 1 wherein the perforated material is a film strip having individual frames containing subject matter to be observed and a row of perforations along one edge thereof to be positioned in alignment with the slot for engagement with the pawl mechanism. 
     
     
       6. The invention in accordance with claim 1 wherein the slot is a narrow elongated aperture positioned adjacent to the larger aperture in the support so that the perforated material can be advanced with the material to be observed in alignment with the larger aperture in the support and perforations aligned with the slot for engagement by the pawl mechanism. 
     
     
       7. The invention in accordance with claim 1 wherein the drive projection is a corrugated member having one free end and fixed in position on the elongated leaf spring, the limit means including a pair of spaced end walls on the support with an aperture in each end wall aligned with the elongated leaf spring member to permit the passage therethrough as the leaf spring member is slid with respect to the slot, an upstanding end stop tab on at least one end of the leaf spring for engagement with the wall to stop movement of the spring in one direction and a downwardly extending tab adjacent the end of the leaf spring distal from the upstanding tab to cooperate with the support in limiting movement of the spring in the opposite direction. 
     
     
       8. The invention in accordance with claim 1 wherein the drive projection is in the form of a U-shaped member fastened at one end to the leaf spring and terminating in the other free end in an annular flange, the limit means including a pair of spaced end walls on the support with an aperture in each end wall aligned with the elongated leaf spring member to permit the passage therethrough as the leaf spring members slid with respect to the slot, an upstanding stop tab on one end of the leaf spring for engagement with the support to limit movement of the spring in one direction and a downwardly extending tab adjacent the other end of the leaf spring to cooperate with the support in limiting movement of the spring in the opposite direction. 
     
     
       9. The invention in accordance with claim 1 wherein the pawl is integrally formed with the leaf spring, the drive projection is a spring like extension intermediate the ends of the leaf spring having a free end for engagement by a portion of the drive means, the limit means including a pair of spaced end walls on the support with an aperture in each end wall aligned with the elongated leaf spring to permit the passage therethrough as the leaf spring member is slid with respect to the slot, an upstanding stop formed on one end of the leaf spring for engagement with the support to limit movement of the leaf spring in one direction and means on the leaf spring and support to limit movement of the leaf spring in the opposite direction, the return means being in the form of a spring loop formed in the elongated spring member mounted on the support so that the loop tends to expand and move the spring in the return direction. 
     
     
       10. An advance mechanism for perforated materials for advancing the material through a path of light comprising: a support structure adapted to be in line with a source of light so that light passes through an aperture in the support;   material support and advance means for directing the perforated material along the pathway into and out of alignment with the aperture;   a pawl mechanism including spring means on the support adjacent the aperture and normally positioned in normal retracted position in alignment with a slot adjacent to the aperture in the support;   drive means for cooperating with the material advance means and for biasing the spring and directing the pawl mechanism through the slot into engagement with a perforation in the material and then along the slot a predetermined distance to advance the material and then releasing the pawl mechanism permitting this spring to return the pawl to the retracted position out of the slot;   return means responsive to release of the pawl mechanism and retraction of the pawl through the slot to return the pawl to normal retracted position;   limit means positioned on the support and on the pawl mechanism to restrict the distance of movement of the pawl mechanism along the length of the slot;   the limit means including at least one enlarged receiving surface on the support and a corresponding enlarged bearing surface on the pawl mechanism whereby movement of the pawl mechanism along the slot a predetermined distance will bring the enlarged bearing surfaces into engagement and stop further movement of the advance mechanism with respect to the slot and with the engagement between the enlarged surfaces distributing the force applied in limiting the movement of the pawl mechanism;   the pawl mechanism including an elongated leaf spring mounted on the support and having a downwardly extending pawl intermediate its ends in alignment with and in position for extension through the slot in the support;   a drive projection extending from the side of the elongated leaf spring opposite to the pawl and in position for engagement by a portion of the drive means;   the elongated leaf spring being slideably positioned on the support so that engagement of the drive means with the drive projection and application of a force thereto will bias the leaf spring until the pawl extends through the slot into engagement with a perforation in the perforated material and then the leaf spring will be slideably moved by the drive means and the perforated material accordingly advanced, and when the drive means is disengaged from the leaf spring, the leaf spring will return to its initial configuration with the pawl disengaged from the perforated material and withdrawn through the slot in the support whereupon the return means can return the leaf spring to the normal retracted position;   the drive means including a cylinder rotatably mounted on the support and adapted to be connected to a drive source;   the cylinder including at least one helical aperture therein in alignment with the aperture in the support and in position for location between a light source and the aperture;   at least one drive cam extending from the outer cylindrical surface of the cylindrical member and in alignment with the drive projection on the surface of the leaf spring, whereupon the actuation of the drive means to rotate the cylindrical member will bring the cam into engagement with the drive projection and initially deflect the leaf spring member downward to engage with the perforated material and than continued rotation of the cylindrical member will slide the leaf spring with respect to the slot thereby advancing the perforated member until continued rotation of the cylindrical member brings the drive cam out of engagement with the leaf spring member.   
     
     
       11. The invention in accordance with claim 10 wherein the position of the helical apertures are arranged with respect to the projecting cams on the circular member so that as the cam drives the leaf spring and advances the perforated member, the helical opening will permit passage of light through the tubular member and through the aperture in the support so that the material on the advanced perforated material will be scanned from left to right by light from the light source in a simultaneous manner. 
     
     
       12. The invention in accordance with claim 10 wherein the drive means includes the cylinder being hollow and having a cross bar on the interior surface thereof intermediate the ends, the cross bar adapted to receive one end of a coupling and the other end of the coupling adapted to be connected to the drive shaft of a motor and to prevent relative rotation of the cylinder with respect to the shaft of the motor and thereby prevent slippage between the cylinder and the drive shaft of the motor. 
     
     
       13. The invention in accordance with claim 10 wherein a drag spring is on the support in alignment with the perforated material and to bias the perforated material against the support structure and in alignment with the pawl mechanism. 
     
     
       14. The invention in accordance with claim 10 wherein the coupling is a member of material of limited flexability with surfaces at one end for engagement with the cylinder to prevent relative rotation therebetween and at the other end for engagement with a motor shaft to prevent relative rotation therebetween so as to couple the cylinder with the motor shaft and, prevent relative rotation between the cylinder, the coupling and the motor shaft while permitting compensation for misalignment. 
     
     
       15. The invention in accordance with claim 14 wherein the drive means includes the cylinder being hollow and having a cross bar on the interior surface thereof intermediate the ends, the cross bar adapted to receive one end of the coupling and the other end of the coupling adapted to be connected to the drive shaft of a motor and to prevent relative rotation of the cylinder with respect to the shaft of the motor and thereby prevent slippage between the cylinder and the drive shaft of the motor, the coupling being a molded member of material of limited flexability with a slot at one end for engagement with the cross arm in the cylinder and having a D-shaped opening in the other end for reception of a D-shaped extension of the motor shaft therein thereby to prevent relative rotation therebetween while permitting compensation for misalignment, the coupling being of polypropylene material. 
     
     
       16. An advance mechanism for perforated materials for advancing the material through a path of light comprising: a support structure adapted to be in line with a source of light so that light passes through an aperture in the support;   material support and advance means for directing the perforated material along the pathway into and out of alignment with the aperture;   a pawl mechanism including spring means on the support adjacent the aperture and normally positioned in normal retracted position in alignment with a slot adjacent to the aperture in the support;   drive means for cooperating with the material advance means and for biasing the spring and directing the pawl mechanism through the slot into engagement with a perforation in the material and then along the slot a predetermined distance to advance the material and then releasing the pawl mechanism permitting this spring to return the pawl to the retracted position out of the slot;   return means responsive to release of the pawl mechanism and retraction of the pawl through the slot to return the pawl to normal retracted position;   limit means positioned on the support and on the pawl mechanism to restrict the distance of movement of the pawl mechanism along the length of the slot;   the limit means including at least one enlarged receiving surface on the support and a corresponding enlarged bearing surface on the pawl mechanism whereby movement of the pawl mechanism along the slot a predetermined distance will bring the enlarged bearing surfaces into engagement and stop further movement of the advance mechanism with respect to the slot and with the engagement between the enlarged surfaces distributing the force applied in limiting the movement of the pawl mechanism;   the pawl mechanism including an elongated leaf spring mounted on the support and having a downwardly extending pawl intermediate its ends in alignment with and in position for extension through the slot in the support;   a drive projection extending from the side of the elongated leaf spring opposite to the pawl and in position for engagement by a portion of the drive means;   the elongated leaf spring being slideably positioned on the support so that engagement of the drive means with the drive projection and application of a force thereto will bias the leaf spring until the pawl extends through the slot into engagement with a perforation in the perforated material and then the leaf spring will be slideably moved by the drive means and the perforated material accordingly advanced, and when the drive means is disengaged from the leaf spring, the leaf spring will return to its initial configuration with the pawl disengaged from the perforated material and withdrawn through the slot in the support whereupon the return means can return the leaf spring to the normal retracted position;   the drive means including a cylinder rotatably mounted on the support and adapted to be connected to a drive source;   the cylinder including at least one helical aperture therein in alignment with the aperture in the support and in position for location between a light source and the aperture;   at least one drive cam extending from the outer cylindrical surface of the cylindrical member and in alignment with the drive projection on the surface of the leaf spring, whereupon the actuation of the drive means to rotate the cylindrical member will bring the cam into engagement with the drive projection and initially deflect the leaf spring member downward to engage with the perforated material and than continued rotation of the cylindrical member will slide the leaf spring with respect to the slot thereby advancing the perforated member until continued rotation of the cylindrical member brings the drive cam out of engagement with the leaf spring member;   the drive means including the cylinder being hollow and having a cross bar on the interior surface thereof intermediate the ends;   the cross bar adapted to receive one end of a coupling and the other end of the coupling adapted to be connected to the drive shaft of a motor and to prevent relative rotation of the cylinder with respect to the shaft of the motor and thereby prevent slippage between the cylinder and the drive shaft of the motor;   the coupling including an end plug having a slot at one end for interengagement with the cross arm in the cylinder and having a cylindrical prong of smaller diameter extending from the other end;   a helical spring having one end mounted on the prong;   a cover tube over the helical spring and the other end over the helical spring adapted to receive the end of a shaft of the motor therein and engage therewith so as to restrict relative rotation between the shaft of the motor and the cylinder.   
     
     
       17. The invention in accordance with claim 16 wherein the coupling is formed with a base and spring of steel and the cover tube is of plastic material shrunk fit on the spring. 
     
     
       18. An advance mechanism for perforated materials for advancing the material through a path of light comprising: a support structure adapted to be in line with a source of light so that light passes through an aperture in the support;   material support and advance means for directing the perforated material along the pathway into and out of alignment with the aperture;   a pawl mechanism including spring means on the support adjacent to the aperture and normally positioned in a normally retracted position in alignment with a slot adjacent to the aperture in the support;   drive means for cooperating with the material advance means and for biasing the spring and directing the pawl mechanism through the slot into engagement with a perforation in the material and then along the slot a predetermined distance to advance the material and then releasing the pawl mechanism permitting this spring to return the pawl to the retracted position out of the slot;   return means responsive to release of the pawl mechanism and retraction of the pawl through the slot to return the pawl to a normally retracted position;   limit means positioned on the support and on the pawl mechanism to restrict the distance of movement of the pawl mechanism along the length of the slot;   the drive means including a rotatable drive cylinder on the support and having means thereon to receive one end of a coupling and the other end of the coupling adapted to be connected directly to the drive shaft of a motor and to prevent relative rotation of the cylinder with respect to the shaft of the motor and thereby prevent slippage between the cylinder and the drive shaft of the motor;   the coupling including an end plug having a slot at one end for interengagement with a corresponding surface in the cylinder and having a cylindrical prong of a smaller diameter extending from the other end;   a helical spring having one end mounted on the prong;   a cover tube over the helical spring and the other end over the helical spring adapted to receive the end of the shaft of the motor therein and engage therewith so as to restrict relative rotation between the shaft of the motor and the cylinder.   
     
     
       19. The invention in accordance with claim 18 wherein the coupling is formed with a base and spring of steel and the cover tube is of plastic material shrunk fit on the spring. 
     
     
       20. An advance mechanism for perforated materials for advancing the material through a path of light comprising: a support structure adapted to be in line with a source of light so that light passes through an aperture in the support;   material support and advance means for directing the perforated material along the pathway into and out of alignment with the aperture;   a pawl mechanism including spring means on the support adjacent the aperture and normally positioned in a normal retracted position in alignment with a slot adjacent to the aperture in the support;   drive means for cooperating with the material advance means and for biasing the spring and directing the pawl mechanism through the slot into engagement with a perforation in the material and then along the slot a predetermined distance to advance the material and then releasing the pawl mechanism permitting this spring to return the pawl to the retracted position out of the slot;   return means responsive to release of the pawl mechanism and retraction of the pawl through the slot to return the pawl to normal retracted position;   limit means positioned on the support and on the pawl mechanism to restrict the distance of movement of the pawl mechanism along the length of the slot;   the drive means including a rotatable drive cylinder on the support and having means thereon to receive one end of a coupling and the other end of the coupling adapted to be connected directly to the drive shaft of a motor and to prevent relative rotation of the cylinder with respect to the shaft of the motor and thereby prevent slippage between the cylinder and the drive shaft of the motor; and   the coupling being a member of material of limited flexability with surfaces at one end for engagement with the cylinder to prevent relative rotation therebetween and at the other end for engagement with a motor shaft to prevent relative rotation therebetween so as to couple the cylinder with the motor shaft and prevent relative rotation between the cylinder, the coupling and the motor shaft while permitting compensation for misalignment.   
     
     
       21. The invention in accordance with claim 20 wherein the drive cylinder includes at least one helical aperture therein, in alignment with the aperture in the support and in position for location between a light source and the aperture at least one drive cam extending from the outer cylindrical surface of the cylindrical member and in alignment with the spring means, whereupon actuation of the drive means to rotate the cylindrical member will bring the drive cam into engagement with the spring producing engagement between the pawl mechanism and a perforation on the material and then continued rotation of the cylindrical member will slide the spring with respect to the slot thereby advancing the perforated material until continued rotation of the cylindrical member brings the drive cam out of engagement with the spring. 
     
     
       22. The invention in accordance with claim 20 wherein the drive means includes the cylinder being hollow and having a cross bar on the interior surface thereof intermediate the ends, the cross bar adapted to receive one end of the coupling and the other end of the coupling adapted to be connected to the drive shaft of a motor and to prevent relative rotation of the cylinder with respect to the shaft of the motor and thereby prevent slippage between the cylinder and the drive shaft of the motor, the coupling being a molded member of material of limited flexability with a slot at one end for engagement with the cross arm in the cylinder and having a D-shaped opening in the other end for reception of a D-shaped extension of the motor shaft therein thereby to prevent relative rotation therebetween while permitting compensation for misalignment, the coupling being of polypropylene materials. 
     
     
       23. The invention in accordance with claim 20 wherein a drag spring is on the support in alignment with the perforated material and to bias the perforated material against the support structure in alignment with the pawl mechanism.